Solution of difficultly water soluble medicinal agents



Patented July 7, 1942 UNITED STATES PATENT OFFICE SOLUTION OF DIFFICULTLY WATER SOLUBLE MEDICINAL AGENTS Otto Schnider, Basel, Switzerland, assignor to Hoflman-La Roche Inc., Nutley, N. J., a corporation of New Jersey No Drawing. Application March 22, 1939, Serial No. 283,547. In Germany May 29,1937

8 Claims.

wherein R represents an alkyl radical containing not more than three carbon atoms, either alone or in combination with water. These compounds may be advantageously-employed, for example, for preparing homogeneous solutions of allyl isopropyl barbituric acid, diethyl barbiturio acid, quinine hydro chloride, camphor, acetyl salicylic acid, and 2,4-dioxo-3,3-diethyl tetrahydro pyridine.

The lower saturated alkyl esters oi! B-acetamino butyric acid of the type specified have been found to be miscible with water in all proportions, as well as being excellent solvents for anncultly soluble medicinal agents. The compounds are only hydrolyzed with difficulty in neutral aqueous solutions. Since their toxicity has been found to be very low, they may be employed even without water in the preparation of medicinal solutions for oral, as well as parenteral, administration. They can be injected in any concentration without producing irritation.

The p-acetamino butyric acid esters are obtained by catalytic hydrogenation of the correspending Z-acetamino crotonic esters with the aid or ordinary catalysts such as palladium or nickel. The reduction may be eflected at atmospheric or raised pressures, depending upon the catalyst chosen. The hydrogenation may be carried out in the presence or absence of solvents.

The following examples further illustrate the invention, but the scope of the invention is not restricted thereto. The parts are parts by weight, unless otherwise stated.

Example 1 arts of allyl isopropyl barbituric acid are treated with a mixture oi 60 parts of fi-acetamino butyric acid ethyl ester and 40 parts oi. water. The resulting solution is clear, colourless and may be further diluted with water, if so desired.

The same result may be obtained by using ,8-

acetamino butyric acid methyl ester instead of B-acetamino butyric acid ethyl ester.

Example 2 25 parts of quinine hydrochloride are dissolved in a mixture or equal parts of p-acetamino butyric acid ethyl ester and water, the total quantity of the solution being brought to 100 parts by volume.

With the same quantity of solubilising agents 8 parts 01 quinine base may be dissolved to a stable solution, which, in case or need, may be further diluted with water.

Example 3 In the same way as given in Example 3, 25 parts of acetyl salicylic acid may be dissolved in 79 parts of p-acetamino butyric acid ethyl ester to a solution of 100 parts by volume.

Example 5 By treating 10 parts 01 2,4-dioxo-3,3-diethyl tetrahydro pyridine with a mixture of 30 parts of p-acetamlno butyric acid ethyl ester and 64 parts of water. a clear and stable solution is obtained, which may be further diluted with water.

Example 6 10 parts of diethyl barbituric acid are dissolved in parts of p-acetamino butyric acid n-propyl ester, whereupon water is added to the solution until the quantity amounts to' parts by volume. The solution is colourless and stable.

I claim:

1. A homogeneous liquid mixture comprising a diilicultly water soluble organic medicinal agent dissolved in a solvent selected from the group consisting of a lower saturated alkyl ester of p-acetamino butyric acid, the alkyl radical oi which contains not more than three carbon atoms, and a lower saturated alkyl ester of pacetamino butyric acid, the alkyl radical 01 which contains not more than three carbon atoms, and water.

2. A homogeneous liquid mixture comprising a difficultly water soluble organic medicinal agent dissolved in a solvent consisting oi. a lower saturated alkyl ester or p-acetamino butyric acid, the alkyl radical 0! which contains not more than three carbon atoms, and water.

3. A homogeneous liquid mixture comprising a difiicultly water soluble organic medicinal agent dissolved in a solvent consisting oi p-acetamino butyric acid ethyl ester and water.

4. A homogeneous liquid mixture comprising an organic hypnotic agent dissolved in a solvent consisting of a lower saturated alkyl ester of p-acetamino butyric acid, the alkyl radical of which contains not more than three carbon atoms, and water.

5. A homogeneous liquid mixture comprising a barbituric acid hypnotic agent dissolved in a solvent consisting of a lower saturated alkyl ester of p-acetamino butyric acid, the alkyl radical of which contains not more than three carbon atoms, and.- water.

6. A homogeneous liquid mixture comprising an allyl isopropyi barbituric acid dissolved in a solvent consisting 01 a lower saturatedaikyi ester of p-acetamino butyric acid, the alkyl radical of which contains not more than three carbon atoms, and water.

7. A homogeneous liquid mixture comprising 2,4-dioxo-3,3-diethybtetrahydro pyridine dissolved in -a solvent consistingfot a lower saturated alkyl ester or ,6=-acetamino butyric acid, the alkyl radical of which contains not more than three carbon atoms, and water.

8. A homogeneous liquid mixture comprising quinine hydrochloride dissolved in a solvent consisting of a lower saturated alkyl ester oi ,B-acetamino butyric acid, the alkyl radical of which contains not more than three carbon atoms, and water.

O'I'IO SCHNTDER. 

